A system having a device such as a pneumatic motor that is operated by compressed air or other pressure gas often includes a regulator whereby the pressure of gas at the device is prevented from exceeding a predetermined value, even though pressure at the source of the gas may be substantially higher than that value. A generally conventional type of regulator for this purpose comprises a body having an inlet port that is connectable with the pressure gas source and an outlet port connectable with the pneumatically operated device. Inside the body is a throttling valve that comprises a poppet-like valve element which is movable toward and from a coaxial annular valve seat to provide a variable restriction to flow of gas from the inlet port to the outlet port. The position of the valve element is controlled by an actuator comprising a diaphragm that is coaxial with the valve element and has one of its surfaces exposed in a pressure chamber communicated with the outlet port while its opposite surface is acted upon by a coaxial helical spring. A coaxial stem that extends through the valve seat serves as a connection between the diaphragm and the valve element. The arrangement is such that the spring, acting through the diaphragm, tends to force the valve element away from its seat, whereas pressure at the outlet port, manifested in the pressure chamber, tends to overcome the biasing force of the spring so that the valve element approaches its seat and increasingly restricts flow through the body as pressure at the outlet port increases.
It is apparent that the pressure which such a regulator maintains at its outlet port--and hence at a pneumatic device connected with that port--is dependent upon the biasing force which the helical spring exerts against the diaphragm. To provide for adjustment of that biasing force, it has heretofore been conventional for the spring of such a regulator to react against an adjustable spring seat that had a threaded connection with the body. Screwing the spring seat inwardly relative to the body increased the biasing force that the spring imposed upon the diaphragm and thus increased the pressure maintained at the outlet port.
Heretofore it has usually been regarded as undesirable to permit quick and easy changes in the pressure to be maintained by a gas pressure regulator, since this could encourage unauthorized tampering that could defeat the purpose of the regulator. From this standpoint it was seen as an advantage that the screw threaded pressure control adjustment was relatively inconvenient to manipulate and required that a substantial length of time be spent in making any substantially large change in adjustment.
By contrast, the present invention is based upon the recognition that certain important and heretofore unappreciated advantages can be gained from the provision of simple, inexpensive and reliable means for adjusting a gas pressure regulator of the general type described above, whereby the value of gas pressure to be maintained at the regulator outlet can be changed almost instantaneously by the mere swinging of a lever and whereby the pressure value for which the regulator is adjusted is accurately denoted by the position of that lever. Specifically, a pressure regulator that is easily and practically instantaneously adjustable as to the pressure that it is to maintain has a versatility not available in prior regulators and can be employed, for example, as a variable speed control for a pneumatic motor with which it is connected.
It is thus a general object of this invention to provide a gas pressure regulator of the type described above which is quickly and easily adjustable to maintain any selected pressure within a stepless range of pressures.
Another object of the invention is to provide means in a gas pressure regulator of the character described whereby the pressure to be maintained by the regulator can be quickly and easily set to any desired value within a stepless range of values, and whereby provision is made for a calibrating adjustment of either the low or the high limit of that range.
In this connection it is a more specific object of the invention to provide simple adjusting structure which comprises a swingable lever or the like whereby pressure maintained by a pressure regulator can at any time be readily adjusted within a stepless range, together with calibration means, intended to be changed only infrequently, whereby the top or the bottom limit of that range can be steplessly adjusted, said structure being supported by a single screw or the like whereby said calibration means can be releasably locked in any position of adjustment in which it is established, and also comprising means cooperating with said screw to frictionally retard displacement of the swinging lever out of any position in which it may be established.
The attainment of the above-stated objectives of the invention results in the attainment of still another object of the invention, and one that is more far-reaching in its significance than those set forth above, namely the provision of a gas pressure regulator which can also serve as a shut-off valve and which is thus capable of fulfilling a triple role as a speed control, shut-off control and pressure regulator. This objective is obtained with the control unit of the present invention in the particular case in which the lower limit of the range of pressure values through which it is transiently adjustable is chosen as zero.
It follows that it is an important object of this invention to provide a single relatively simple and inexpensive control unit which can in many cases function very satisfactorily as the only control unit needed in a pneumatic system in which it is installed.
It is thus another object of the invention to provide a simple but very versatile control unit for a pneumatic system, which is, at most, only slightly more expensive than a heretofore conventional gas pressure regulator but which makes possible the elimination or omission of other control units in a pneumatic system in which it is incorporated, thus affording substantial reductions in the cost, complexity and bulkiness of the system while at the same time rendering the system substantially more reliable and easier to control.
Another and more specific object of the invention is to provide a control unit comprising a combined pressure regulator and shut-off valve of the character described that is particularly suitable for installation in automotive and similar systems by reason of being relatively immune to the effects of vibration, said unit having means for preventing pressure build-ups in portions of the system downstream from the unit that might result from vibration.